Question

A hydrogen atom emits a photon that has momentum with a magnitudeof
6.81 10-27 kg m/s.
Thisphoton is emitted because the electron in the atom falls from
ahigher energy level into the n = 1 level. What is
thequantum number of the level from which the electron falls? Use
avalue of 6.626 10-34 J s for
Planck'sconstant.ninitial = 1